In different contexts there is a need for a correct alignment of different components in relation to each other. In connection with operation of e.g. machines and fan constructions, the outgoing power is often transmitted from a propelling unit via a rotational movement of a shaft and a first component for power transmission to a second component for power transmission, which together with a further shaft form a part of a propelled unit. The components for power transmission can in turn be arranged for, by way of example, chain propulsion or belt propulsion. When belt propulsion is used, the power is transmitted via one or more belts which are tightened over two components in the form of belt discs which are aligned with each other.
At transmissions of the type belt propulsion, it is essential that the belt discs are aligned in relation to each other such that the belt discs are arranged with an extension along a common imaginary plane, which in turn results in that the belts are allowed to run over the belt discs completely straight without being effected by any lateral force. A misalignment of the belt discs may otherwise lead to an unnecessarily high wear of the belts and belt discs and an unnecessarily high power consumption (i.e. a reduced degree of efficiency) of the machines for which the belt discs are used.
In particular, alignment of belt discs is intended to reduce or preferably eliminate possible parallel errors, angular errors and so called twist errors between the belt discs. The term parallel error means that the belt discs have their extensions along two different planes which are parallel in relation to each other. Angular error means that those planes along which the belt discs are arranged have a certain angle in relation to each other. Twist errors means that those planes along which the belt discs are arranged have been turned to a different degree along an imaginary longitudinal line which runs along the centre of the belt discs.
By a correct alignment, it can be seen to that the belt discs are placed along a common plane without the occurrence of any of the above-mentioned errors.
From the Swedish patent application SE 0000024-0, filed by the same applicant as the present application, an arrangement for alignment of belt discs is previously known. This arrangement comprises a first measuring unit and a second measuring unit, where the respective measuring unit is arranged for generation of laser light in the direction towards each other and for detection of incident light from the opposite unit. By detecting the incident light, it may be established if the position of the two belt discs has to be adjusted in relation to each other.
Although this known device provides an accurate detection and a reliable function, there is a need for continued improvements within the current technical field.